By: Martin Lee, Jey Hwan Lee, Wilson Leung

Background Former HKIA, replaced in 1998 ▫World’s busiest in 1997 ▫Overcrowded World famous difficult landings into runway 13 ▫North end: 6 stories high buildings ▫Often used due to prevailing wind directions ▫Visual approach required

After retiring… Land used for development ▫Sports Stadium ▫Cruise Terminal ▫Hotel ▫Etc… From Maunsell AECOM Asia Ltd Contaminated land detected: ▫Ex-Government Flying Services (ex-GFS) ▫South of North Apron ▫South Apron

Causes & Hazards Causes: ▫Underground fuel hydrant leakages ▫Oil Companies Tank Farm leakages ▫Workers pouring fuel over pavement Contaminants: ▫Total Petroleum Hydrocarbon (TPH)  Toluenes and Xylenes (BTEX)  Methane (in explosive concentrations) ▫Heavy Metals  Polyaromatic Hydrocarbons  Polychlorinated Biphenyls Hazards: ▫No explosive hazard as concrete layer seals underground contaminants from open air ▫Toluene causes Nausea ▫Xylenes cause headaches, lung issues, muscle co-ordination problems

Remediation Options Bioremediation Soil Vapour Extraction Air Sparging Dual-phase extraction Low-Temp. Thermal Desorption Chemical Oxidation Bio-pile Capping Cement stabilisation/solidification Landfarming

Remediation Adopted 1.Soil Vapour Extraction (SVE) ▫Air Sparging 2.Bio-pile 3.Bioremediation Mitigating Environmental Effects: 1.Vapour Emission Treatment Systems 2.Oil Interceptors 3.Noise Silencers

Soil Vapour Extraction/Air Sparging - Method Method 1.Drill Wells into soil above W.T. 2.Apply Vacuum Pressure 3.Underground vapour pulled out 4.Air treatment system collects vapours 5.Separates contaminants from air 6.Contaminants disposed safely

Soil Vapour Extraction/Air Sparging - Application Pros: ▫Simple to install & maintain ▫Safe and natural process ▫Minimal disturbances to soil profile Cons: ▫Empirical Design, no theoretical equations ▫Doesn’t deal with soils under W.T. ▫Cannot deal with low conc. In-situ Removes subsurface contaminants, such as Volatile Organic Compounds (VOC)

Bio-pile - Method Method 1.Identify soil characteristics 2.Excavate soil 3.Mix excavated soil with soil amendments 4.Heap contaminated soils into piles 5.Enclose the contaminated soil 6.Contaminants removed through controlled aerobic microbial activity

Bio-pile - Application Pros: ▫Simple to design and implement ▫Short treatment times (6 months – 2 years) ▫Relatively cheap (30-90 USD/ton of contaminated soil) ▫Closed system (vapor emissions controlled) Cons: ▫Require a large land area for treatment ▫Not effective for high constituent concentrations ▫Volatile constituent tend to evaporate rather than biodegrade during treatment Ex-situ Used to reduce concentrations of petroleum constituent products through biodegradation

Bioremediation - Method 1.Wells injected to groundwater level 2.Calcium Nitrate solution is pumped into soil through wells 3.Oxygen and water is occasionally supplied to wells 4.Solution is spread throughout contaminated areas 5.Extraction wells collects groundwater for further water treatment.

Bioremediation - Application In-situ Injection of calcium nitrate to promote growth of NRSOB Eliminates odour from degradation of organic compounds caused by SRB Pros: ▫Natural process ▫Easily conducted on-site ▫Efficient, Satisfactory result, short time ▫Little or acceptable environmental impact ▫Low cost Cons: ▫Requires constant monitoring to ensure effectiveness ▫Takes a little longer than some techniques ▫Little knowledge on its long term effect on areas of multiple contamination

Conclusion First and largest of its kind in HK ▫No effective legislation to guide decontamination in right direction Combined methods protected 700,000 people incl. residents & workers Effectively cleaned almost 19000m 2 of contaminated land